1. Field of the Invention
The present invention relates to means for the transfer of loads from one level to another. More particularly the invention relates to means allowing for the transfer of loads between two adjacent floors or storeys of a building structure.
2. Description of the Prior Art
A conventional elevator, of the type suitable for transferring loads from one level to another, depends for its actual operation upon the utilisation of steel cables, hoisting ropes or the like. Such elevators in general may be seen to comprise a power operated device for lifting and lowering loads and are made up of a so-called car or cage which is arranged so as to run between guide rails extending between the levels under consideration. The car or cage itself is by convention suspended from steel hoisting ropes or cables. The weight of the car and its load is, in practice, approximately counter-balanced by a so-called counterweight. The actual weight to be hoisted by the drive motor may therefore be seen never to equal the total weight of the car and passengers (or load) but rather is equal to merely the relatively small difference which exists between the counterweight and the weight of the loaded car.
By reason of the use of steel hoisting cables, ropes and the like the relevant government authorities require the incorporation of sophisticated and virtually fail-safe safety devices and safe-guards in elevators of this general type. Some elevators, for example, are equipped with a safety rope which runs in an endless loop around pulleys positioned at the top and bottom respectively of the lift well or shaft. This safety rope is then secured to the lift or elevator car. In the event of fracture or failure of the hoisting rope or cable the car will drop (under the influence of gravity). This drop will cause the pulleys of the safety rope to rotate more rapidly. A centrifugal governor connected to the safety rope pulley positioned at the top of the lift shaft will then serve to actuate a switch which will set the safety devices in operation whereby to arrest the downward motion of the car. In one example this arresting effect is achieved by means of powerful jaws adapted to act on and grip the guide rails.